FULL PRODUCT VERSION :
java version "1.7.0_67"
java version "1.8.0_20"


ADDITIONAL OS VERSION INFORMATION :
Mac Book 2,3 GHz Intel Core i5 Mac OS X 10.9.4

A DESCRIPTION OF THE PROBLEM :
1. Create simple GUI containing combo box:

JComboBox comboBox = new JComboBox();
comboBox.addItem("Combo Box Item 1");
comboBox.addItem("Combo Box Item 1");

2. Compiile and execute on Mac Book with Mountain Lion or later.
3. Click combo box, select item in popup menu.
4. Repeat several times.
5. Observe eventually selection isn't updated.


REGRESSION. Last worked in version 6u43


REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
After creating comboBox:

ItemListener[] itemListeners = comboBox.getItemListeners();
comboBox.removeItemListener(itemListeners[0]); // AquaComboBoxUI

Note that AquaComboBoxUI createItemListener only does something when multiple items are selected.